1. Field of the Invention
This invention relates to hepatitis B Dane particles and, more particularly, to a process for preparing hepatitis B Dane particles in high yield and purity.
Hepatitis B is one of the types of viral hepatitis which results in a systemic infection with the principal pathologic changes occurring in the liver. This disease affects mainly adults and is maintained chiefly by transfer of infection from long term carriers of the virus. Usual methods of spread are by blood transfusion, contaminated needles and syringes, through skin breached by cuts or scratches, by unsterilized dental instruments as well as by saliva, veneral contact or exposure to aerosolized infected blood.
The incubation period of type B hepatitis is relatively long: from 6 weeks to 6 months may elapse between infection and the onset of clinical symptoms. The illness usually begins with fatique and anorexia, sometimes accompanied by myalgia and abdominal discomfort. Later jaundice, dark urine, light stools and tender hepatomegaly may appear. In some cases, the onset may be rapid, with appearance of jaundice early in association with fever, chills and leukocytosis. In other cases jaundice may never be recognized and the patient may be aware of a "flu-like" illness. It is estimated that the majority of hepatitis infections result in a mild, anicteric illness.
2. Background of the Invention
Serum obtained from patients with hepatitis B infections contains three distinct morphologic forms which share a common surface antigen (HB.sub.s Ag) and which can be aggregated with specific antibody directed against HB.sub.s Ag. The largest of these morphologic forms, a 42-nm to 45-nm double shelled spherical particle, often referred to as the Dane particle (HBV), is believed to be the virus of hepatitis B. The outer surface or envelope of the Dane particle surrounds a 27-nm inner core which does not react with antibody against HB.sub.s Ag and which contains a distinct antigen, the core antigen (HB.sub.c Ag). Antibody to HB.sub.c Ag appears after acute hepatitis B infection, and also can be demonstrated consistently in chronic carriers of HB.sub.s Ag. Highly sensitive techniques are now available for detection of the HB.sub.c Ag-Ab system. A deterrent to the more widespread use of such techniques, however, is the absence of a simple yet effective method for obtaining Dane particles from which HB.sub.c Ag may be prepared.
3. Objects of the Invention
It is, accordingly, an object of the present invention to provide an improved method for obtaining Dane particles. Another object is to provide a method for concentrating and purifying Dane particles. These and other objects of the present invention will be apparent from the following description.